"Le Boudin"
Boudin gave rise to "Le Boudin", the official march of the French Foreign Legion. "Blood sausage" is a colloquial reference to the gear (rolled up in a red blanket) that used to top the backpacks of Legionnaires. The song makes repeated reference to the fact that the Belgians don't get any "blood sausage", since the King of the Belgians at one time forbade his subjects from joining the Legion (verse says "ce sont des tireurs au cul").
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